ai-code-battle/cmd/acb-api/server.go

package main

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/redis/go-redis/v9"
)

// Server is the v1 API server for AI Code Battle.
// Provides bot registration, job coordination, replay serving,
// bot profiles, leaderboards, and UI feedback ingestion.
type Server struct {
	cfg Config
	db  *sql.DB
	rdb *redis.Client
}

func (s *Server) RegisterRoutes(mux *http.ServeMux) {
	// Health endpoints
	mux.HandleFunc("GET /health", s.handleHealth)
	mux.HandleFunc("GET /ready", s.handleReady)

	// Bot registration
	mux.HandleFunc("POST /api/register", s.handleRegister)

	// Job coordination (for workers)
	mux.HandleFunc("GET /api/job", s.handleGetJob)
	mux.HandleFunc("POST /api/job/", s.handleJobResult)

	// Replay serving
	mux.HandleFunc("GET /api/replay/", s.handleGetReplay)

	// Bot profiles and leaderboard
	mux.HandleFunc("GET /api/bot/", s.handleGetBot)
	mux.HandleFunc("GET /api/bots", s.handleListBots)

	// Community replay feedback per plan §13.6
	mux.HandleFunc("POST /api/feedback", s.handleUIFeedback)

	// Predictions
	mux.HandleFunc("POST /api/predict", s.handlePredict)
	mux.HandleFunc("GET /api/predictions/open", s.handleOpenPredictions)
	mux.HandleFunc("GET /api/predictions/history", s.handlePredictionHistory)
}

func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(v)
}

func writeError(w http.ResponseWriter, status int, msg string) {
	writeJSON(w, status, map[string]string{"error": msg})
}

// handleRegister handles POST /api/register
// Request body: {"name": "...", "owner": "...", "endpoint_url": "..."}
// Response: {"bot_id": "...", "shared_secret": "..."}
func (s *Server) handleRegister(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	var req struct {
		Name        string `json:"name"`
		Owner       string `json:"owner"`
		EndpointURL string `json:"endpoint_url"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	// Validate required fields
	if req.Name == "" || req.Owner == "" || req.EndpointURL == "" {
		writeError(w, http.StatusBadRequest, "name, owner, and endpoint_url are required")
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	// Check if name is already taken
	var existingID string
	err := s.db.QueryRowContext(ctx, "SELECT bot_id FROM bots WHERE name = $1", req.Name).Scan(&existingID)
	if err == nil {
		writeError(w, http.StatusConflict, fmt.Sprintf("bot name '%s' is already taken", req.Name))
		return
	} else if err != sql.ErrNoRows {
		log.Printf("database error checking bot name: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}

	// Generate bot ID and shared secret
	botID, err := generateID("b_", 6)
	if err != nil {
		log.Printf("failed to generate bot ID: %v", err)
		writeError(w, http.StatusInternalServerError, "failed to generate bot ID")
		return
	}

	sharedSecret, err := generateSecret()
	if err != nil {
		log.Printf("failed to generate secret: %v", err)
		writeError(w, http.StatusInternalServerError, "failed to generate secret")
		return
	}

	// Encrypt the shared secret
	var encryptedSecret string
	if s.cfg.EncryptionKey != "" {
		encryptedSecret, err = encryptSecret(sharedSecret, s.cfg.EncryptionKey)
		if err != nil {
			log.Printf("failed to encrypt secret: %v", err)
			writeError(w, http.StatusInternalServerError, "failed to encrypt secret")
			return
		}
	} else {
		// If no encryption key configured, store plaintext (not recommended for production)
		encryptedSecret = sharedSecret
	}

	// Validate bot is reachable by sending a health check
	if err := s.validateBotEndpoint(ctx, req.EndpointURL); err != nil {
		writeError(w, http.StatusBadRequest, fmt.Sprintf("bot endpoint validation failed: %v", err))
		return
	}

	// Insert bot into database
	_, err = s.db.ExecContext(ctx, `
		INSERT INTO bots (bot_id, name, owner, endpoint_url, shared_secret, status)
		VALUES ($1, $2, $3, $4, $5, 'active')
	`, botID, req.Name, req.Owner, req.EndpointURL, encryptedSecret)
	if err != nil {
		log.Printf("failed to insert bot: %v", err)
		writeError(w, http.StatusInternalServerError, "failed to register bot")
		return
	}

	log.Printf("registered bot %s (name=%s, owner=%s)", botID, req.Name, req.Owner)

	writeJSON(w, http.StatusCreated, map[string]string{
		"bot_id":        botID,
		"shared_secret": sharedSecret,
	})
}

// validateBotEndpoint checks if the bot endpoint is reachable
func (s *Server) validateBotEndpoint(ctx context.Context, endpointURL string) error {
	// Remove trailing slash for consistency
	endpointURL = strings.TrimRight(endpointURL, "/")

	// Try to GET /health endpoint with a timeout
	healthURL := endpointURL + "/health"
	client := &http.Client{Timeout: time.Duration(s.cfg.BotTimeoutSecs) * time.Second}

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, healthURL, nil)
	if err != nil {
		return fmt.Errorf("invalid endpoint URL: %w", err)
	}

	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("endpoint unreachable: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("health check returned status %d", resp.StatusCode)
	}

	return nil
}

// handleGetJob handles GET /api/job
// Workers poll this endpoint to get the next pending match job.
// Requires Bearer token authentication (worker API key).
// Response: job JSON or empty if no jobs available.
func (s *Server) handleGetJob(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	// Authenticate worker
	if !s.authenticateWorker(r) {
		writeError(w, http.StatusUnauthorized, "invalid or missing worker API key")
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	// Query for the next pending job
	var job struct {
		JobID      string          `json:"job_id"`
		MatchID    string          `json:"match_id"`
		ConfigJSON json.RawMessage `json:"config_json"`
	}

	err := s.db.QueryRowContext(ctx, `
		SELECT job_id, match_id, config_json
		FROM jobs
		WHERE status = 'pending'
		ORDER BY created_at ASC
		LIMIT 1
		FOR UPDATE SKIP LOCKED
	`).Scan(&job.JobID, &job.MatchID, &job.ConfigJSON)

	if err == sql.ErrNoRows {
		// No pending jobs
		writeJSON(w, http.StatusOK, map[string]string{"status": "no_jobs"})
		return
	} else if err != nil {
		log.Printf("database error getting job: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}

	// Parse config_json to get match details
	var config struct {
		MapID     string `json:"map_id"`
		MapSeed   int64  `json:"map_seed"`
		BotIDs    []string `json:"bot_ids"`
		PlayerSlots []int `json:"player_slots"`
	}
	if err := json.Unmarshal(job.ConfigJSON, &config); err != nil {
		log.Printf("failed to parse job config: %v", err)
		writeError(w, http.StatusInternalServerError, "invalid job config")
		return
	}

	// Get map data
	var mapData struct {
		MapID      string          `json:"map_id"`
		GridWidth  int             `json:"grid_width"`
		GridHeight int             `json:"grid_height"`
		MapJSON    json.RawMessage `json:"map_json"`
	}
	err = s.db.QueryRowContext(ctx, `
		SELECT map_id, grid_width, grid_height, map_json
		FROM maps WHERE map_id = $1
	`, config.MapID).Scan(&mapData.MapID, &mapData.GridWidth, &mapData.GridHeight, &mapData.MapJSON)
	if err != nil {
		log.Printf("failed to get map: %v", err)
		writeError(w, http.StatusInternalServerError, "map not found")
		return
	}

	// Get bot endpoints and secrets
	bots := make([]map[string]interface{}, 0, len(config.BotIDs))
	for _, botID := range config.BotIDs {
		var endpointURL, encryptedSecret string
		err := s.db.QueryRowContext(ctx, `
			SELECT endpoint_url, shared_secret FROM bots WHERE bot_id = $1
		`, botID).Scan(&endpointURL, &encryptedSecret)
		if err != nil {
			log.Printf("failed to get bot %s: %v", botID, err)
			writeError(w, http.StatusInternalServerError, "bot not found")
			return
		}

		// Decrypt secret if encryption key is configured
		var sharedSecret string
		if s.cfg.EncryptionKey != "" {
			sharedSecret, err = decryptSecret(encryptedSecret, s.cfg.EncryptionKey)
			if err != nil {
				log.Printf("failed to decrypt secret for bot %s: %v", botID, err)
				// Fall back to treating it as plaintext
				sharedSecret = encryptedSecret
			}
		} else {
			sharedSecret = encryptedSecret
		}

		bots = append(bots, map[string]interface{}{
			"bot_id":        botID,
			"endpoint_url":  endpointURL,
			"shared_secret": sharedSecret,
		})
	}

	// Build response
	response := map[string]interface{}{
		"job_id":        job.JobID,
		"match_id":      job.MatchID,
		"map_id":        config.MapID,
		"map_seed":      config.MapSeed,
		"map_width":     mapData.GridWidth,
		"map_height":    mapData.GridHeight,
		"map_json":      mapData.MapJSON,
		"bots":          bots,
		"player_slots":  config.PlayerSlots,
	}

	writeJSON(w, http.StatusOK, response)
}

// handleJobResult handles POST /api/job/{id}/result
// Workers submit match results here.
// Requires Bearer token authentication.
// Request body: {"winner": "...", "turns": 123, "end_reason": "...", "scores": {...}, "replay": {...}}
func (s *Server) handleJobResult(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	// Authenticate worker
	if !s.authenticateWorker(r) {
		writeError(w, http.StatusUnauthorized, "invalid or missing worker API key")
		return
	}

	// Extract job ID from path: /api/job/{id}/result
	pathParts := strings.Split(r.URL.Path, "/")
	if len(pathParts) < 4 || pathParts[3] != "result" {
		writeError(w, http.StatusBadRequest, "invalid path")
		return
	}
	jobID := pathParts[2]

	var req struct {
		WinnerID  string          `json:"winner"`
		Turns     int             `json:"turns"`
		EndReason string          `json:"end_reason"`
		Scores    map[string]int  `json:"scores"`
		Replay    json.RawMessage `json:"replay"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 10*time.Second)
	defer cancel()

	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		log.Printf("failed to begin transaction: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}
	defer tx.Rollback()

	// Get match ID for this job
	var matchID string
	err = tx.QueryRowContext(ctx, "SELECT match_id FROM jobs WHERE job_id = $1", jobID).Scan(&matchID)
	if err == sql.ErrNoRows {
		writeError(w, http.StatusNotFound, "job not found")
		return
	} else if err != nil {
		log.Printf("failed to get job: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}

	// Update job status
	_, err = tx.ExecContext(ctx, `
		UPDATE jobs SET status = 'completed', completed_at = NOW() WHERE job_id = $1
	`, jobID)
	if err != nil {
		log.Printf("failed to update job: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}

	// Determine winner player index
	var winnerIndex *int
	if req.WinnerID != "" {
		var idx int
		err := tx.QueryRowContext(ctx, `
			SELECT player_slot FROM match_participants WHERE match_id = $1 AND bot_id = $2
		`, matchID, req.WinnerID).Scan(&idx)
		if err == nil {
			winnerIndex = &idx
		}
	}

	// Update match status
	scoresJSON, _ := json.Marshal(req.Scores)
	_, err = tx.ExecContext(ctx, `
		UPDATE matches
		SET status = 'completed', winner = $1, condition = $2, turn_count = $3, scores_json = $4, completed_at = NOW()
		WHERE match_id = $5
	`, winnerIndex, req.EndReason, req.Turns, scoresJSON, matchID)
	if err != nil {
		log.Printf("failed to update match: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}

	// Update participant scores
	for botID, score := range req.Scores {
		_, err = tx.ExecContext(ctx, `
			UPDATE match_participants SET score = $1 WHERE match_id = $2 AND bot_id = $3
		`, score, matchID, botID)
		if err != nil {
			log.Printf("failed to update participant score: %v", err)
		}
	}

	// Note: Rating updates are handled by the worker separately via the rating endpoint
	// or can be computed here if the ratings are provided in the request

	// Resolve predictions for this match
	if err := s.resolvePredictions(ctx, tx, matchID, req.WinnerID); err != nil {
		log.Printf("failed to resolve predictions for match %s: %v", matchID, err)
	}

	if err := tx.Commit(); err != nil {
		log.Printf("failed to commit transaction: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}

	log.Printf("completed job %s, match %s, winner %s", jobID, matchID, req.WinnerID)

	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

// handleGetReplay handles GET /api/replay/{id}
// Serves replay JSON from R2 warm cache with B2 fallback.
func (s *Server) handleGetReplay(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	// Extract match ID from path: /api/replay/{id}
	pathParts := strings.Split(strings.TrimPrefix(r.URL.Path, "/api/replay/"), "/")
	if len(pathParts) == 0 || pathParts[0] == "" {
		writeError(w, http.StatusBadRequest, "invalid match ID")
		return
	}
	matchID := pathParts[0]

	ctx, cancel := context.WithTimeout(r.Context(), 30*time.Second)
	defer cancel()

	// First, try to get from R2 warm cache
	// This requires R2 credentials to be configured
	replayData, err := s.fetchReplayFromR2(ctx, matchID)
	if err == nil {
		w.Header().Set("Content-Type", "application/json")
		w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
		w.WriteHeader(http.StatusOK)
		w.Write(replayData)
		return
	}
	log.Printf("R2 fetch failed for %s: %v", matchID, err)

	// Fall back to B2 cold archive
	replayData, err = s.fetchReplayFromB2(ctx, matchID)
	if err == nil {
		w.Header().Set("Content-Type", "application/json")
		w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
		w.Header().Set("X-ACB-Source", "b2")
		w.WriteHeader(http.StatusOK)
		w.Write(replayData)
		return
	}

	log.Printf("B2 fetch also failed for %s: %v", matchID, err)
	writeError(w, http.StatusNotFound, "replay not found")
}

// fetchReplayFromR2 attempts to fetch a replay from R2 warm cache
func (s *Server) fetchReplayFromR2(ctx context.Context, matchID string) ([]byte, error) {
	// R2 endpoint and credentials would be configured via environment variables
	r2Endpoint := "https://r2.aicodebattle.com" // Default R2 endpoint
	if env := getEnv("ACB_R2_ENDPOINT", ""); env != "" {
		r2Endpoint = env
	}

	url := fmt.Sprintf("%s/replays/%s.json.gz", r2Endpoint, matchID)

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}

	client := &http.Client{Timeout: 10 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("R2 returned status %d", resp.StatusCode)
	}

	return io.ReadAll(resp.Body)
}

// fetchReplayFromB2 attempts to fetch a replay from B2 cold archive
func (s *Server) fetchReplayFromB2(ctx context.Context, matchID string) ([]byte, error) {
	// B2 endpoint and credentials would be configured via environment variables
	b2Endpoint := "https://b2.aicodebattle.com" // Default B2 endpoint
	if env := getEnv("ACB_B2_ENDPOINT", ""); env != "" {
		b2Endpoint = env
	}

	url := fmt.Sprintf("%s/replays/%s.json.gz", b2Endpoint, matchID)

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}

	client := &http.Client{Timeout: 10 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("B2 returned status %d", resp.StatusCode)
	}

	return io.ReadAll(resp.Body)
}

// handleGetBot handles GET /api/bot/{id}
// Returns bot profile JSON including rating, record, and metadata.
func (s *Server) handleGetBot(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	// Extract bot ID from path: /api/bot/{id}
	pathParts := strings.Split(strings.TrimPrefix(r.URL.Path, "/api/bot/"), "/")
	if len(pathParts) == 0 || pathParts[0] == "" {
		writeError(w, http.StatusBadRequest, "invalid bot ID")
		return
	}
	botID := pathParts[0]

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	// Get bot details
	var bot struct {
		BotID      string  `json:"bot_id"`
		Name       string  `json:"name"`
		Owner      string  `json:"owner"`
		Status     string  `json:"status"`
		RatingMu   float64 `json:"rating_mu"`
		RatingPhi  float64 `json:"rating_phi"`
		Evolved    bool    `json:"evolved"`
		Island     *string `json:"island,omitempty"`
		Generation *int    `json:"generation,omitempty"`
		ParentIDs  *string `json:"parent_ids,omitempty"`
		CreatedAt  string  `json:"created_at"`
		LastActive *string `json:"last_active,omitempty"`
	}

	err := s.db.QueryRowContext(ctx, `
		SELECT bot_id, name, owner, status, rating_mu, rating_phi,
		       evolved, island, generation, parent_ids,
		       to_char(created_at, 'YYYY-MM-DD\"T\"HH24:MI:SSZ') as created_at,
		       to_char(last_active, 'YYYY-MM-DD\"T\"HH24:MI:SSZ') as last_active
		FROM bots WHERE bot_id = $1
	`, botID).Scan(
		&bot.BotID, &bot.Name, &bot.Owner, &bot.Status,
		&bot.RatingMu, &bot.RatingPhi, &bot.Evolved,
		&bot.Island, &bot.Generation, &bot.ParentIDs,
		&bot.CreatedAt, &bot.LastActive,
	)

	if err == sql.ErrNoRows {
		writeError(w, http.StatusNotFound, "bot not found")
		return
	} else if err != nil {
		log.Printf("database error getting bot: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}

	// Calculate win/loss record
	var wins, losses int
	err = s.db.QueryRowContext(ctx, `
		SELECT
			COUNT(*) FILTER (WHERE mp.bot_id = $1 AND m.winner = (
				SELECT player_slot FROM match_participants WHERE match_id = m.match_id AND bot_id = $1
			)) as wins,
			COUNT(*) FILTER (WHERE mp.bot_id = $1 AND m.winner IS NOT NULL AND m.winner != (
				SELECT player_slot FROM match_participants WHERE match_id = m.match_id AND bot_id = $1
			)) as losses
		FROM match_participants mp
		JOIN matches m ON mp.match_id = m.match_id
		WHERE mp.bot_id = $1 AND m.status = 'completed'
	`, botID).Scan(&wins, &losses)
	if err != nil {
		log.Printf("error getting bot record: %v", err)
		// Continue without record data
	}

	// Build response
	response := map[string]interface{}{
		"bot_id":      bot.BotID,
		"name":        bot.Name,
		"owner":       bot.Owner,
		"status":      bot.Status,
		"rating":      bot.RatingMu - 2*bot.RatingPhi, // Conservative rating estimate
		"rating_mu":   bot.RatingMu,
		"rating_phi":  bot.RatingPhi,
		"evolved":     bot.Evolved,
		"island":      bot.Island,
		"generation":  bot.Generation,
		"parent_ids":  bot.ParentIDs,
		"created_at":  bot.CreatedAt,
		"last_active": bot.LastActive,
		"record": map[string]int{
			"wins":   wins,
			"losses": losses,
		},
	}

	writeJSON(w, http.StatusOK, response)
}

// handleListBots handles GET /api/bots
// Returns leaderboard snapshot of all active bots.
func (s *Server) handleListBots(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	// Parse query parameters for pagination
	limit := 100
	offset := 0
	if l := r.URL.Query().Get("limit"); l != "" {
		if n, err := strconv.Atoi(l); err == nil && n > 0 && n <= 1000 {
			limit = n
		}
	}
	if o := r.URL.Query().Get("offset"); o != "" {
		if n, err := strconv.Atoi(o); err == nil && n >= 0 {
			offset = n
		}
	}

	// Query active bots ordered by rating
	rows, err := s.db.QueryContext(ctx, `
		SELECT b.bot_id, b.name, b.owner, b.rating_mu, b.rating_phi,
		       b.evolved, b.island, b.generation,
		       to_char(b.created_at, 'YYYY-MM-DD\"T\"HH24:MI:SSZ') as created_at,
		       COALESCE(wins.wins, 0) as wins, COALESCE(losses.losses, 0) as losses
		FROM bots b
		LEFT JOIN (
			SELECT mp.bot_id, COUNT(*) FILTER (WHERE m.winner = mp.player_slot) as wins
			FROM match_participants mp
			JOIN matches m ON mp.match_id = m.match_id
			WHERE m.status = 'completed'
			GROUP BY mp.bot_id
		) wins ON b.bot_id = wins.bot_id
		LEFT JOIN (
			SELECT mp.bot_id, COUNT(*) FILTER (WHERE m.winner IS NOT NULL AND m.winner != mp.player_slot) as losses
			FROM match_participants mp
			JOIN matches m ON mp.match_id = m.match_id
			WHERE m.status = 'completed'
			GROUP BY mp.bot_id
		) losses ON b.bot_id = losses.bot_id
		WHERE b.status = 'active'
		ORDER BY (b.rating_mu - 2*b.rating_phi) DESC
		LIMIT $1 OFFSET $2
	`, limit, offset)
	if err != nil {
		log.Printf("database error listing bots: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}
	defer rows.Close()

	bots := make([]map[string]interface{}, 0)
	for rows.Next() {
		var bot struct {
			BotID      string  `json:"bot_id"`
			Name       string  `json:"name"`
			Owner      string  `json:"owner"`
			RatingMu   float64 `json:"rating_mu"`
			RatingPhi  float64 `json:"rating_phi"`
			Evolved    bool    `json:"evolved"`
			Island     *string `json:"island,omitempty"`
			Generation *int    `json:"generation,omitempty"`
			CreatedAt  string  `json:"created_at"`
			Wins       int     `json:"wins"`
			Losses     int     `json:"losses"`
		}
		err := rows.Scan(
			&bot.BotID, &bot.Name, &bot.Owner, &bot.RatingMu, &bot.RatingPhi,
			&bot.Evolved, &bot.Island, &bot.Generation, &bot.CreatedAt,
			&bot.Wins, &bot.Losses,
		)
		if err != nil {
			log.Printf("error scanning bot: %v", err)
			continue
		}

		bots = append(bots, map[string]interface{}{
			"bot_id":     bot.BotID,
			"name":       bot.Name,
			"owner":      bot.Owner,
			"rating":     bot.RatingMu - 2*bot.RatingPhi,
			"rating_mu":  bot.RatingMu,
			"rating_phi": bot.RatingPhi,
			"evolved":    bot.Evolved,
			"island":     bot.Island,
			"generation": bot.Generation,
			"created_at": bot.CreatedAt,
			"record": map[string]int{
				"wins":   bot.Wins,
				"losses": bot.Losses,
			},
		})
	}

	if rows.Err() != nil {
		log.Printf("error iterating bots: %v", rows.Err())
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"bots":   bots,
		"limit":  limit,
		"offset": offset,
		"count":  len(bots),
	})
}

// handlePredict handles POST /api/predict
// Accepts {match_id, bot_id, confidence, predictor_id} and writes to predictions table.
// Rejects if the match has already started (status != 'pending').
func (s *Server) handlePredict(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	var req struct {
		MatchID    string `json:"match_id"`
		BotID      string `json:"bot_id"`
		Predictor  string `json:"predictor_id"`
		Confidence *int   `json:"confidence"` // optional 1-100
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	if req.MatchID == "" || req.BotID == "" || req.Predictor == "" {
		writeError(w, http.StatusBadRequest, "match_id, bot_id, and predictor_id are required")
		return
	}

	if req.Confidence != nil && (*req.Confidence < 1 || *req.Confidence > 100) {
		writeError(w, http.StatusBadRequest, "confidence must be between 1 and 100")
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	// Verify match exists and hasn't started
	var matchStatus string
	err := s.db.QueryRowContext(ctx, `
		SELECT status FROM matches WHERE match_id = $1
	`, req.MatchID).Scan(&matchStatus)
	if err == sql.ErrNoRows {
		writeError(w, http.StatusNotFound, "match not found")
		return
	} else if err != nil {
		log.Printf("database error checking match: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}

	if matchStatus != "pending" {
		writeError(w, http.StatusConflict, "match has already started")
		return
	}

	// Verify bot is a participant in this match
	var participantExists bool
	err = s.db.QueryRowContext(ctx, `
		SELECT EXISTS(
			SELECT 1 FROM match_participants
			WHERE match_id = $1 AND bot_id = $2
		)
	`, req.MatchID, req.BotID).Scan(&participantExists)
	if err != nil {
		log.Printf("database error checking participant: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}
	if !participantExists {
		writeError(w, http.StatusBadRequest, "bot is not a participant in this match")
		return
	}

	// Insert prediction (UNIQUE constraint handles duplicates)
	var predictionID int64
	err = s.db.QueryRowContext(ctx, `
		INSERT INTO predictions (match_id, predictor_id, predicted_bot, confidence)
		VALUES ($1, $2, $3, $4)
		ON CONFLICT (match_id, predictor_id) DO UPDATE SET predicted_bot = $3, confidence = $4
		RETURNING id
	`, req.MatchID, req.Predictor, req.BotID, req.Confidence).Scan(&predictionID)
	if err != nil {
		log.Printf("failed to insert prediction: %v", err)
		writeError(w, http.StatusInternalServerError, "failed to submit prediction")
		return
	}

	resp := map[string]interface{}{
		"id":         predictionID,
		"match_id":   req.MatchID,
		"predicted":  req.BotID,
		"predictor":  req.Predictor,
	}
	if req.Confidence != nil {
		resp["confidence"] = *req.Confidence
	}

	writeJSON(w, http.StatusCreated, resp)
}

// handleOpenPredictions handles GET /api/predictions/open
// Returns pending matches that are open for predictions, along with
// any predictions the requesting predictor has made.
func (s *Server) handleOpenPredictions(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	predictorID := r.URL.Query().Get("predictor_id")

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	// Get pending matches with their participants
	rows, err := s.db.QueryContext(ctx, `
		SELECT m.match_id, m.created_at,
		       COALESCE(json_agg(json_build_object('bot_id', mp.bot_id, 'name', b.name, 'rating', b.rating_mu - 2*b.rating_phi)) FILTER (WHERE mp.bot_id IS NOT NULL), '[]')
		FROM matches m
		JOIN match_participants mp ON m.match_id = mp.match_id
		JOIN bots b ON mp.bot_id = b.bot_id
		WHERE m.status = 'pending'
		GROUP BY m.match_id, m.created_at
		ORDER BY m.created_at ASC
		LIMIT 20
	`)
	if err != nil {
		log.Printf("database error fetching open matches: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}
	defer rows.Close()

	type MatchPrediction struct {
		MatchID     string          `json:"match_id"`
		CreatedAt   string          `json:"created_at"`
		Participants []map[string]interface{} `json:"participants"`
		YourPick    *string         `json:"your_pick,omitempty"`
	}

	var matches []MatchPrediction
	for rows.Next() {
		var m MatchPrediction
		var participantsJSON string
		if err := rows.Scan(&m.MatchID, &m.CreatedAt, &participantsJSON); err != nil {
			log.Printf("error scanning match: %v", err)
			continue
		}
		json.Unmarshal([]byte(participantsJSON), &m.Participants)

		// If predictor_id given, look up their existing prediction
		if predictorID != "" {
			var predictedBot string
			err := s.db.QueryRowContext(ctx, `
				SELECT predicted_bot FROM predictions
				WHERE match_id = $1 AND predictor_id = $2
			`, m.MatchID, predictorID).Scan(&predictedBot)
			if err == nil {
				m.YourPick = &predictedBot
			}
		}

		matches = append(matches, m)
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"matches": matches,
	})
}

// resolvePredictions marks open predictions as correct/incorrect and updates predictor_stats.
func (s *Server) resolvePredictions(ctx context.Context, tx *sql.Tx, matchID string, winnerBotID string) error {
	var rows *sql.Rows
	var err error

	if winnerBotID == "" {
		rows, err = tx.QueryContext(ctx, `
			UPDATE predictions
			SET correct = false, resolved_at = NOW()
			WHERE match_id = $1 AND correct IS NULL
			RETURNING predictor_id, correct
		`, matchID)
	} else {
		rows, err = tx.QueryContext(ctx, `
			UPDATE predictions
			SET correct = (predicted_bot = $1), resolved_at = NOW()
			WHERE match_id = $2 AND correct IS NULL
			RETURNING predictor_id, correct
		`, winnerBotID, matchID)
	}
	if err != nil {
		return fmt.Errorf("failed to resolve predictions: %w", err)
	}
	defer rows.Close()

	for rows.Next() {
		var predictorID string
		var correct bool
		if err := rows.Scan(&predictorID, &correct); err != nil {
			return fmt.Errorf("failed to scan resolved prediction: %w", err)
		}
		if err := s.upsertPredictorStats(ctx, tx, predictorID, correct); err != nil {
			return fmt.Errorf("failed to update predictor_stats for %s: %w", predictorID, err)
		}
	}
	return nil
}

// upsertPredictorStats updates the predictor_stats row for a single resolution.
func (s *Server) upsertPredictorStats(ctx context.Context, tx *sql.Tx, predictorID string, correct bool) error {
	if correct {
		_, err := tx.ExecContext(ctx, `
			INSERT INTO predictor_stats (predictor_id, correct, streak, best_streak, updated_at)
			VALUES ($1, 1, 1, 1, NOW())
			ON CONFLICT (predictor_id) DO UPDATE SET
				correct = predictor_stats.correct + 1,
				streak = predictor_stats.streak + 1,
				best_streak = GREATEST(predictor_stats.best_streak, predictor_stats.streak + 1),
				updated_at = NOW()
		`, predictorID)
		return err
	}
	_, err := tx.ExecContext(ctx, `
		INSERT INTO predictor_stats (predictor_id, incorrect, streak, best_streak, updated_at)
		VALUES ($1, 1, 0, 0, NOW())
		ON CONFLICT (predictor_id) DO UPDATE SET
			incorrect = predictor_stats.incorrect + 1,
			streak = 0,
			updated_at = NOW()
	`, predictorID)
	return err
}

// handlePredictionHistory handles GET /api/predictions/history
// Returns resolved predictions for a predictor, used for polling resolution status.
func (s *Server) handlePredictionHistory(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	predictorID := r.URL.Query().Get("predictor_id")
	if predictorID == "" {
		writeError(w, http.StatusBadRequest, "predictor_id is required")
		return
	}

	limitStr := r.URL.Query().Get("limit")
	limit := 20
	if limitStr != "" {
		if l, err := strconv.Atoi(limitStr); err == nil && l > 0 && l <= 100 {
			limit = l
		}
	}

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	rows, err := s.db.QueryContext(ctx, `
		SELECT p.id, p.match_id, p.predicted_bot,
		       COALESCE(wb.name, p.predicted_bot) AS predicted_name,
		       p.correct, p.confidence, p.created_at, p.resolved_at,
		       m.status AS match_status, m.winner,
		       COALESCE(CASE WHEN m.winner IS NOT NULL THEN
		           (SELECT b.name FROM match_participants mp2 JOIN bots b ON mp2.bot_id = b.bot_id
		            WHERE mp2.match_id = m.match_id AND mp2.player_slot = m.winner)
		       END, '') AS winner_name
		FROM predictions p
		JOIN matches m ON p.match_id = m.match_id
		LEFT JOIN bots wb ON p.predicted_bot = wb.bot_id
		WHERE p.predictor_id = $1
		ORDER BY COALESCE(p.resolved_at, p.created_at) DESC
		LIMIT $2
	`, predictorID, limit)
	if err != nil {
		log.Printf("database error fetching prediction history: %v", err)
		writeError(w, http.StatusInternalServerError, "database error")
		return
	}
	defer rows.Close()

	type PredictionEntry struct {
		ID            int64   `json:"id"`
		MatchID       string  `json:"match_id"`
		PredictedBot  string  `json:"predicted_bot"`
		PredictedName string  `json:"predicted_name"`
		Correct       *bool   `json:"correct"`
		Confidence    *int    `json:"confidence,omitempty"`
		CreatedAt     string  `json:"created_at"`
		ResolvedAt    *string `json:"resolved_at,omitempty"`
		MatchStatus   string  `json:"match_status"`
		WinnerName    string  `json:"winner_name,omitempty"`
	}

	var predictions []PredictionEntry
	for rows.Next() {
		var p PredictionEntry
		var createdAt time.Time
		var resolvedAt sql.NullTime
		var winnerName sql.NullString
		var winnerSlot sql.NullInt64

		if err := rows.Scan(&p.ID, &p.MatchID, &p.PredictedBot, &p.PredictedName,
			&p.Correct, &p.Confidence, &createdAt, &resolvedAt,
			&p.MatchStatus, &winnerSlot, &winnerName); err != nil {
			log.Printf("error scanning prediction: %v", err)
			continue
		}

		p.CreatedAt = createdAt.Format(time.RFC3339)
		if resolvedAt.Valid {
			s := resolvedAt.Time.Format(time.RFC3339)
			p.ResolvedAt = &s
		}
		if winnerName.Valid {
			p.WinnerName = winnerName.String
		}
		predictions = append(predictions, p)
	}

	if predictions == nil {
		predictions = []PredictionEntry{}
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"predictions": predictions,
	})
}

// handleUIFeedback handles POST /api/feedback
// Accepts community replay feedback per plan §13.6 (annotations, issues, etc.).
// Stores in database or logs to disk.
func (s *Server) handleUIFeedback(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	var req struct {
		MatchID  string                 `json:"match_id"`
		Turn     int                    `json:"turn"`
		Type     string                 `json:"type"` // "annotation", "issue", "suggestion"
		Message  string                 `json:"message"`
		Metadata map[string]interface{} `json:"metadata,omitempty"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	// Validate required fields
	if req.MatchID == "" || req.Type == "" {
		writeError(w, http.StatusBadRequest, "match_id and type are required")
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	// Try to store in database if ui_feedback table exists
	metadataJSON, _ := json.Marshal(req.Metadata)
	_, err := s.db.ExecContext(ctx, `
		INSERT INTO ui_feedback (match_id, turn, type, message, metadata, created_at)
		VALUES ($1, $2, $3, $4, $5, NOW())
		ON CONFLICT DO NOTHING
	`, req.MatchID, req.Turn, req.Type, req.Message, metadataJSON)

	if err != nil {
		// If table doesn't exist, log to file instead
		log.Printf("[UI-FEEDBACK] match=%s turn=%d type=%s: %s", req.MatchID, req.Turn, req.Type, req.Message)
		// Still return success to not break the UI
	} else {
		log.Printf("[UI-FEEDBACK] stored: match=%s turn=%d type=%s", req.MatchID, req.Turn, req.Type)
	}

	writeJSON(w, http.StatusCreated, map[string]string{"status": "recorded"})
}

// authenticateWorker checks if the request has a valid worker API key
func (s *Server) authenticateWorker(r *http.Request) bool {
	authHeader := r.Header.Get("Authorization")
	if authHeader == "" {
		return false
	}

	// Expect "Bearer {api_key}"
	parts := strings.SplitN(authHeader, " ", 2)
	if len(parts) != 2 || parts[0] != "Bearer" {
		return false
	}

	return parts[1] == s.cfg.WorkerAPIKey
}

func getEnv(key, defaultValue string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return defaultValue
}